Rheostat.



PATENTEDJULYBO, 1907. F. G. JAHN. RHEOSTAT.

APPLICATION FILED DEO.8,1904.

s SHEETS-SHEET 1.'

PETERS 4.0., w-Asmua ou, ov c.

1101 1365. PATENTEDJULY so, 1907.

F. G. JAHN.

RHBOSI'AT. APYLIOATIOH FILED DEO.8,1904.

' 3 SHEETS-SHEET 2- PATENTED JULY 30,1907. F. G. JAHN. 4 RHEOSTAT. APPLICATION FILED DBO.8,1904.

3 SHBETS-SHEET 3.

UNITED STATES PATENT OFFICE.

FREDERICK G. JAHN, OF NEW YORK, N. Y., ASSIGNOR TO THE INTERNATIONAL POSTAL SUPPLY COMPANY OF NEW YORK, OF BROOKLYN, NEW YORK, A OOR'PORATION OF NEW YORK.

RHEOSTAT.

Specification of Letters Patent.

Patented July 30, 1907.

To all whom it may concern:

Be it known that I, FREDERICK G. JAIIN, a citizen of the United States, residing at borough of Brooklyn, city of New York, county of Kings, and State of N ew York, have invented certain new and useful 1mprovements in Rheostats, of which the following is a specification.

The present invention relates to rheostats such for instance as those commonly known as motor starters and as speed controllers, and in this case capable of use as either or for both.

It has for its object to generally improve and simplify the construction and mode of operation of the rheostat and to increase its general efficiency and reliability to the end that it will instantly and automatically respond to any excessive load on the motor due for instance to the clogging of the machinery it drives, to an excess in current passing to the motor or to an increase in the current beyond the safety point due to too suddenly closing the circuit. And it furthermore has for its object to provide means by which the motor may be effectively stopped through the instrumentality of the rheostat mechanism, instead of depending as heretofore on an independent circuit breaking or line switch.

The improved construction in its preferred form consists of a movable circuit closing arm arranged to close the circuit between a single live contact and either one of a plurality of independent contacts with interposed resistance coils and to break the circuit when resting against a dead piece or pieces. Between the single live contact and the line there is interposed an automatic circuit breaker, which circuit is otherwise normally closed, and which consists, preferably, of a pair of separable contacts and a solenoid magnet, the movable core of which, should for instance an excess of current or too high a rise in amperage occur, will be forcibly propelled through the magnet to separate or move one of the separable contacts away from the other to break the circuit and thus instantaneously relieve the motor of any increase of current beyond the point of safety. This automatic breaking of the circuit compels the return of the circuit closing arm to its dcac or initial position and this return movement is made the means of returning the separable contacts into correct relation with each other, so that when said arm is again and not too suddenly moved the circuit through the arm to the motor will be maintained until another occasion for the automatic circuit breaking action arises. The separable contacts and the circuit closing arm are furthermore made the means, when the motor is to be stopped, for breaking the circuit through the instrumentality of said arm at its initial return movement and immediately before it leaves the final independfor attachment in the position for use.

out contact to pass on to the next preceding contact,

so that all sparking between the surfaces of the arm and the independent contacts is prevented and its use as a means of stopping the motor as well as for starting it, is rendered feasible and practical. With this general understanding of the improvement a detailed description of a practical embodiment thereof will now be given, reference being had to the accompan ying drawings, in which:

Figure 1, is a front elevation. Fig. 2, is a vertical cross section on the line 2, 2, of Fig. 1. Fig. 3, is a rear elevation. Fig. 4, is an elevation of the aniomatic circuit breaker showin the parts in their moved or circuit breaking position. Fig. 5, is a detail sectional elevation of the circuit closing rm and its immediate parts. Fig. (5, is a sectional detail of modification taken on the plane of the supporting plate looking from the rear; and Fig. '7, is a sectional side elevation of the same. Fig. 8, is a diagram of the circuits through the rheostat and motor.

The parts of the improved rlieostat are supported by a single stone slab or other suitable plate B, arranged The front or exposed face of the plate supports independent electric contacts or segments 10,11, 12, 1.3 and 1 1, a long electric contact or segment 15, diametrically opposed to said five independent segments and two diametrically opposed dear contacts or segments D, D the whole being grouped in circular form around a coinmon horizontal axis. With these segments there coae'ts a movable circuit closing arm 16, centrally mounted at said axis and having at each of its free ends bearing faces for surface contact with the several segments and to make contact between diametrically opposed portions of the circular arrangement of segments. On the rear of the supporting plate B, four resistance coils between the five electric contacts or segments are preferably provided by two resistance pieces C each piece carrying two independent portions of the resistance, supported by cast iron cores 4O fl with suitable insulation.

The circuit closing arm l (S, is centrally carried on a horizontal oscillatory rod 17, that is mounted to turn in a comparatively long hub-like bearing 18, secured to the supporting plate B, through its outer head or flange 19. The circuit closing arm and horizontal rod 17, are moved by a hand-lever 20, secured to the outer end of the rod and is arranged to move more or less freely and remain in any position to which it may be moved between two limiting stops 2l, 22, the lever abutting faces of which are covered with soft rubber or other noise deadening substance. The circuit closing arm l6, is loose on the horizontal rod, and connection between it and the hand lever is bad by a stud 23, Fig5, of fiber or other insulating material carried on senses 11 of the lever and entering a recess in the front face of the arm, and a washer 24, of similar material is interposed between the arm and hand-lever around the rod 17. The rear end of the horizontal rod 17, has fast to it an arm 25, forming an abutment for a fiber or similar disk 26, loose on the rod and between which and the rear of the supporting plate and encircling the rod is a coiled spring 27, the action of which tends to constantly pull the circuit closing arm into firm surface contact with the surface of the circular arrangement of segments. The washer 24, between the contact arm and hand-lever has one surface convcxed to fit a concaved seat in the face of the arm 16, Fig-2, and at the same time inter-pose a bushing between the arm and the rod and thus thoroughly insulate the arm from the rod and from the hand-lever and at the same time providing a joint adapting the contact arm to adjust itself in surface bearing contact with the segments independent of the proper alinement of the horizontal rod or the proper surface adjustment of the contact or segments. The spring 27, also serves to hold the circuit closing arm and hand-lever together and with sufficient frictional contact against the segments to allow said arm and lover to remain in whatever position they may be moved without danger of jar affecting such position.

At or near the limit of the circuit closing movement of the arm 16, there is arranged a contact piece or post 38, having a yielding spring-pressed pin 39, see Fig. l, in electric connection with the binding post F, Figs. 3 & 8, against which post or its yielding pin the end of the arm will bear as soon as it moves to fully close the circuit with the last independent contact 14, so that the current which would otlmrwisc have to pass through all the resistances to the post F, will be short circuited through the arm and contact piece 38, to said post F.

The electric circuit is held normally closed between the source of electric energy or line and the long segment 15, but is rendered breakable by an automatic circuit breaking device E, consisting of a so called knife-switch and a solenoid magnet 34. In this instance the switch consists of a rocking contact linger 30, coacting with a pair of spring contact blades 3]., the linger being pivotally mounted to a post 32, and having a weighted end 29, to facilitate its breaking movement, and the spring contact blades are secured fast to a post 33, both posts extending from the rear of the supporting plate. The movable finger is held in circuit closing position by the friction thereon of the spring contact blades, it being otherwise free to move by reason of its weighted end.

The contact finger 30, is positively moved between the spring blades by a fiber or similar pin 28, fixed to the arm 25, of the horizontal rod 17 which arm and pin are so arranged with respect to the circuit closing arm and hand-lever that when the arm is in its initial position resting against the two dead segments D, D and the hand-lever is against the off limiting stop 21, the separable contacts 30 and 31, will be in electric contact and the circuit will be closed between the source of electric energy or line and the long segment 15, while the continuity of said circuit to the motor will be broken by the dew position of the circuit closing arm 16, as in Figs1, 2 and 3.

The solenoid magnet 34, included in said circuit to the separable contacts 30, 3]., is of the usual form having the downwardly extended shell secured in a bearing 35, fast to the rear of the supporting plate b, thus holding the magnet axially immediately below the rocking contact finger 30, of the separable contacts. The magnet core 36, movable through the center of the magnet, has at its upper end a fiber or similar button 2, for striking and moving the movable finger 30. The down or normal position of the core 36, in the magnet is determined by an adjustable screw 37, threaded into the bearing 35, its head forming a seat for the end of the core, as in Fig2. The position of this core will be adjusted to allow a stated normal current to pass through the magnet and thence to the motor without energizing said magnet sufficient to move the core. But after the circuit closing arm had been moved to close the circuit to the motor and has thereby removed the pin 28, from position innnediately above the movable finger 30, should the current exceed the normal safety amperage the magnet. will be instantly energized and the core forcibly drawn upwardlytherein to move the contact finger 30, from the spring blades 31, and thus break the circuit to the motor, as indicated in Fig f. When this occurs the hand-lever will be moved to return the circuit closing arm back to its dea( or initial position thereby through the movement of the pin 28, returning the contact finger 30, into contact with the spring blades as in Fig-3.

As before stated the automatic breaking of the circuit may be made to occur from any one of the several causes enumerated and the improved rheostat may be made or adjusted to care for any one or all of such occasions.

Where the current is heavier say than two or three amperes it is desirous in order to prevent sparking and the consequent burning of the independent contacts and circuit closing arm 16, to wholly break the circuit'to the motor. In the present instance, see Figs-6 and 7, the circuit closing arm and the separable contacts of the automatic circuit breaker are made the instrumentalities by which this may be effected, thereby providing a single accessible device for stopping as well as starting the motor. The contact finger 30, is fast to one end of its pivot spindle 46, the other end carrying a short arm 3, projecting into the path of movement of a spring seated stud 1, carried in a. projection from the circuit closing arm lti. When the said arm 16, is moved to the final independent contact 1 1, in starting the motor the stud 4;, yields idly past the short arm 3, but when it is desired to stop the motor innnediately the circuit closing arm lti, is started in its return movement in the direction of the arrow Fig-6, and before its bearing surface wholly leaves said.contact 1 1, and touches the next preceding contact 13, the stud 1, will have struck and so far moved the short arm 3, as to have rocked the contact finger 30, away from the spring blades 31, to break the circuit to the motor. As the circuit closing arm is returned to its initial dead position, the pin 28, will have acted to return the contact finger 30, to its current closing position.

From what has been described the electric circuits through the improved rheostatwill be rendered clear from an examination of the diagram Fig8. It

simply remains to be set forth that the line a connects with the binding post L, thence through the coils of the solenoid magnet 34, through the separable contacts 31 and 30, to the single long segment 15. The current then passes by the circuit closing arm 16, when it is moved from its deac position to the first independent contact 10, through the resistances 0, G and other independent contacts 11 to 14, and from said .last contact to the binding post A, thence to one of the brushes of the motor M, through its armature and the other brush to the line b. A portion of the current passes from the initial independent contact 10, through the posts 38 and F, to the field oi the motor, and as the circuit closing armmoves over the contacts to the last one this portion of the circuit passes through the successive resistances to the motor field, successively growing weaker as the current to the motor armature grows stronger, until the arm finally rests on said last contact 14, and the whole strength of the current passes to the armature. At this time, however, a short circuit is formed between the end of the circuit closing arm and the contact piece 38, making the circuit irom the arm to the binding post F, and thence through the motor field and one of the brushes to the line b, so that the current to the field need .not traverse the resistances.

From the foregoing it will be understood that the improved structure as a whole provides a rheostat oi' exceeding simplicity and wherein the mechanical members and the wiring and connections may be viewed at a glance so that any ditliculty in its proper working will be immediately detected and easily remedied. Its availability is also enhanced in that the necessity for a wholly separable and independent circuit breaker or line switch is avoided.

What is claimed is:

1. A resistance circuit including a circuit closer cooperating successively with the resistances therein, and man ually operated in both directions, separable contacts inde pendent of said circuit closer and its contacts and a mag net adapted when energized by a rise in the current to sep arate said separable contacts by the direct impact of its armature.

A resistance circuit including a circuit closer coiiper atinesuccessively with the resistances therein, and man ually operated in both directions, separable contacts independent of said circuit closer and its contacts, a magnet adapted when energized by a rise in the current to separate said separable contacts by the direct impact of its armature and means operated by the circuit closer to restore the separable contacts.

3. A resistance circuit including a circuit closer cooperatine; successively with the resistances therein, separable contacts and means connected with the circuit closer i'or first separating said contacts in the initial movement of said circuit closer to its oft position and then restoring said contacts on its arrival at said position.

4:. A resistance circuit including a circuit closer cooperating successively with the resistances therein, separable contacts, means connected with the circuit closer for first separating: said contacts in the initial movement of said circuit closer to its off position and then restoringsaid contacts on its arrival at said position and a magnet for automatically separating the contacts on a rise in the cur rent.

A resistance circuit including" a circuit closer cooperating successively with the resistances therein, separable contacts, means for automatically separating said separa blc contacts on a rise in current and means connected with the circuit closer for separating the separable contacts.

6. The combination of a resistance circuit, an inde pendent circuit breaker including a magnet to automatic ally operate the same, and a circuit closer cooperating with both and manually operated in both directions to both make and break the circuit.

T. The combination of two pairs of independent sepa rable contacts in a circuit and a single instrumentaliiy manually operated in both directions with means coi5perating with both pair oi contacts to independently close and break the circuit with each pair.

S. A resistance circuit including a circuit closing arm, a pair of im'lependent separable contacts separable to break the circuit independent of the movement ol' the closing arm and means carried by said arm for separating said contacts.

5). A resistance circuit including a circuit closing arm, manually operated in both directions, an independent pair of separable contacts, means movable with said arm in closing the circuit through the resistances to insure also the closing of the circuit through said separable contacts, means for automatically breakingthe circuit through said separable contacts and on the reverse movement of said arm to break the circuit through the separable contacts.

10. A resistance circuit including" a circuit closer therefor manually operated in both directions and having an insulated projection carried therewith, and an automatic circuit breaking mechanism the movable contact of which is idly mounted and adapted to be moved in one direction by the direct push of said mechanism and in the other direction by the direct act of the circuit closer and projection.

11. An axially supported circuit closing, arm, an insulating bushing; between said arm and its axial support and a sprin for i'rictionally holding the arm, bushing and sup port together.

12. A circuit closing arm loosely mounted on a rocksha'ft an interposed insulating ball bearing bushing, a hand-lever fast to said shall: and having insulated connection with said arm and a springfor holding the arm and bushing frictionally together.

13. A rheostat consisting 01 a supporting plate having on its front face resistance and line contacts, a circuit closing arm supported in hearings in the plate and coopcrating with said contacts, and said plate having on its rear face the resistance coils, a pair of separable contacts coupled by the act of said arm and also a magnet adapted on a rise in current to separate said contacts by the direct impact of its armature.

]-l. A rheostat consisting of a circular arrangement of contacts, a two armed lever cooperating therewith, scp arable contacts coupled in the act of moving the lever in one direction and a magnet the armature of which is adapted to contact with and separate the separable con tacts on a rise in the current 15. A rheostat consisting of a circular arrangement of contacts, a two armed lever cooperating therewith, separable contacts separated in the initial movement of said lever in the 01? direction and restored as its final act in arriving at the oft position.

In testimony whereof, i have signed my name to this specification in the presence ot two subscribing witnesses, this 7th day oi December 1004.

FREDERICK G. .TAHN.

A. 'l. DOLPHIN. 

